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Standard Interpretations - (Archived) Table of Contents
• Standard Number: 1910.147; 1910.147(a)(2)(ii)
• Status: Archived

Archive Notice - OSHA Archive

NOTICE: This is an OSHA Archive Document, and may no longer represent OSHA Policy. It is presented here as historical content, for research and review purposes only.

June 11, 2003

Name Withheld

Thank you for your January 28 letter to the Occupational Safety and Health Administration (OSHA) regarding a United States Postal Service (USPS) Lockout/Tagout procedure specific to the Multiple Line Optical Character Recognition (MLOCR) sorter. This letter constitutes OSHA's interpretation only of the requirements discussed and may not be applicable to any questions not delineated within your original correspondence. Your paraphrased scenario, question, and our response are provided below:

Scenario: I received training from the USPS in the use of lockout and tagout devices. During the training it was made quite clear that a machine must be locked out if "an employee is required to place any part of his or her body into an area on a machine or piece of equipment where work is actually being performed upon the material being processed (point of operation) or where an associated danger exists during a machine operating cycle."

Recently I read a part from a Postal Service Maintenance Management Order MMO-058-01 that said: "Work, which is genuinely minor or routine, that occurs while the (MLOCR) equipment is in production mode (e.g., during mail processing) can be performed without locking out. It also stated that "the employee must be protected from unexpected startup, application of power, or release of stored energy by alternative, protective measures such as: a pressed emergency stop or an interlocked cover and a delayed startup with warning lights or buzzers." This seems to state that an emergency stop, interlock, or a delayed startup with warning light or buzzers is sufficient means to protect employees from unexpected startup, and does not appear to be in alignment with my training requiring lockout devices or tagout devices to protect from unexpected startups.

Question: Is the procedure in MMO-058-01 relating to the MLOCR sorter compliant with OSHA requirements?

Reply: The OSHA lockout/tagout standard (29 CFR 1910.147) covers the servicing and maintenance of machines and equipment when the unexpected energization or start up, or release of stored energy, could injure employees. However, as described in the "minor servicing" exception under 29 CFR 1910.147(a)(2)(ii), "[m]inor tool changes and adjustments, and other minor servicing activities, which take place during normal production operations, are not covered by this standard if they are routine, repetitive, and integral to the use of the equipment for production, provided that the work is performed using alternative measures which provide effective protection (See subpart O of this part)."

The "minor servicing" exception generally contemplates servicing or maintenance that does not require significant disassembly of machines or equipment and may apply to, for example, changing label and ribbon stock, clearing paper jams, minor cleaning (including lens cleaning), and making certain adjustments. Therefore, the exception under 1910.147(a)(2)(ii) could apply to your scenario; if so, the equipment noted in your letter need not be locked out or tagged out, provided an alternative, effective type of protection is provided for employees.

During minor servicing activities, an employer may meet the requirement for providing an alternative, effective type of protection by using special tools or safeguarding techniques. In addition, several alternative means of safeguarding the hazardous portions of the machines and equipment during their operation are presented by the national consensus standard, ANSI B11.19-1990. Some of the safeguards include: interlocked barrier guards, presence sensing devices, and various safeguarding devices under the exclusive control of the employee.

In 1994, as a result of citations issued by OSHA to some postal facilities using Parcel Bar Code Sorters, the Postal Service's Office of Safety and Health in Washington, D.C. revised some Lockout/Tagout procedures and invited OSHA and the Postal Workers Union to verify abatement of the citations. A team of professionals from OSHA's National Office reviewed the videos, procedures, and standards and found the procedures to contain the following redundant means for removing energy from the printer head:
  1. Preset button;
  2. Start Button;
  3. Interlock on the access door with audible alarm when opened; and
  4. Emergency stop button relays along the side of the conveyor belts that would remove energy from the printer heads.
The team believed that the procedure met the guarding requirements of Subpart O (alternative measures) and that lockout/tagout was necessary only when servicing or maintenance work did not meet all of the criteria set forth in the minor servicing, 1910.147(a)(2)(ii), exception. As a result, an internal memorandum (copy enclosed) from OSHA's National Office to OSHA's Regional Administrator, Region VIII was issued on this subject.

The MMO-058-01 procedure included with your letter did not provide sufficient information to allow us to determine if an alternative, effective type of protection required under 1910.147(a)(2)(ii) is provided.
1 The examples cited in the procedure: "the use of pressed emergency stop" and an "interlocked cover with delayed startup with warning light or buzzers," do not adequately describe whether they safeguard the danger zones while "minor servicing" activities, excepted under 1910.147(a)(2)(ii), are being performed. For example, it is not clear whether the emergency stops are used alone, or in conjunction with other interlocked cover mechanisms.

The use of emergency stops
2 alone does not provide the alternative, effective type of protection required under 1910.147(a)(2)(ii). Furthermore, the information in the procedure regarding the use of an "interlocked cover with delayed startup with warning light or buzzers" is not adequately described to allow us to determine if the mechanism ("interlocked cover") offers an equivalent safeguarding method, as would be provided by methods, such as "interlocked barrier guards," prescribed in ANSI B11.19-1990.

Additionally, the procedure states that lockout of electric energy is not required for servicing or maintenance on equipment that operates at less than 50 volts to ground, provided no additional hazards are present. Please note that the 50-volt exception applies only to lockout/tagout procedures required under 1910.333(b) for working on or near energized parts of electric circuits. If the servicing or maintenance exposes employees to non-electrical hazards, the lockout/tagout provisions of 1910.147 apply, regardless of the type or magnitude of the energy.

Thank you for your interest in occupational safety and health. We hope you find this information helpful. OSHA requirements are set by statute, standards, and regulations. Our interpretation letters explain these requirements and how they apply to particular circumstances, but they cannot create additional employer obligations. This letter constitutes OSHA's interpretation of the requirements discussed. Note that our enforcement guidance may be affected by changes to OSHA rules. Also, from time to time we update our guidance in response to new information. To keep apprised of such developments, you can consult OSHA's website at
http://www.osha.gov. If you have any further questions, please feel free to contact the Office of General Industry Enforcement at (202) 693-1850.


Richard E. Fairfax, Director
Directorate of Enforcement Programs

1 OSHA does not test, approve, certify, or endorse any equipment or product, including procedures. [back to text]

2 Emergency stops are not safeguarding devices and generally do not provide the required level of employee control. [back to text]

Archive Notice - OSHA Archive

NOTICE: This is an OSHA Archive Document, and may no longer represent OSHA Policy. It is presented here as historical content, for research and review purposes only.

Standard Interpretations - (Archived) Table of Contents

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